In mobile, fixed broadband, and data center application fields, there is a requirement for sequentially concatenating multiple value-added services for a specific application service flow of a specific user. For example, in a mobile or fixed broadband application, for an HTTP (Hypertext transfer protocol, Hypertext Transfer Protocol) or web (web page) Internet access service flow, three value-added services, namely, content filtering, a cache service, and a firewall, need to be sequentially concatenated before Internet (Internet, Internet) access. For a video service flow, only two value-added services, namely, a cache service and a firewall, need to be sequentially concatenated without content filtering. For an encrypted service flow, only a firewall value-added service is required. Likewise, there is also a similar application requirement in a service chain scenario in a data center application. For example, for some service flows in a data center, two value-added services, namely, a firewall and wide area network application acceleration, need to be sequentially concatenated.
Value-added services are concatenated to form a service chain (service chain), and applied as a whole to traffic of a user that subscribes to the services. Properly orchestrating and managing the service chain help an operator quickly deploy and apply a new type of service in a network and quickly provide or change a service template subscribed to by the user.
Currently, to implement a service chain, a service chain orchestrator generally delivers policy routing information, piece by piece according to a sequence of service nodes (Service Node, SN) that the service needs to pass through, to each service node on the service chain path separately by using a centralized controller or a conventional network management system, and even to a router on an intermediate non-service node, to ensure end-to-end smoothness of a flow to which the service chain is applied.
In this service chain implementation controlled and managed in a centralized manner, a route reachability status of each adjacent service node on a service chain forwarding path needs to be monitored, and multipoint control and coordination need to be performed on multiple SNs on the service chain forwarding path to ensure that the flow on the service chain is smooth. Therefore, load of a centralized control and management device is relatively heavy, and service chain deployment is relatively difficult.